Liquid-liquid interfacial self-assembled Au NP arrays for the rapid and sensitive detection of butyl benzyl phthalate (BBP) by surface-enhanced Raman spectroscopy

Abstract

Recent years have seen a large number of incidents involving the contamination of liquor with phthalate plasticizers (PAEs). There is therefore an urgent need to develop novel analytical strategies for the rapid and sensitive detection of PAEs. The PAE butyl benzyl phthalate (BBP) is very harmful to the human body, so we developed a surface-enhanced Raman spectroscopy (SERS) platform for the rapid detection of BBP in liquor based on liquid-liquid extraction and the simultaneous self-assembly of arrays of Au nanoparticles (Au NPs) at an organic/aqueous interface. The self-assembly of Au NPs occurs under the influence of the surface tension at the interface between the immiscible solvents. In the first step of the strategy, cyclohexane (CYH) is mixed with BBP-containing liquor to extract the BBP. Then the self-assembly of Au NPs at an organic/aqueous interface is induced using the CYH supernatant as the organic phase, a colloid of Au NPs as the aqueous phase, and ethanol as the inducer. During this process, the BBP molecules extracted from the liquor participate directly in the Au NP self-assembly process, which causes the analytes to be loaded into SERS-active nanogaps in the Au NP arrays, thus permitting the sensitive detection of BBP. BBP levels as low as 1.3 mg/kg in the liquor were detected using this method. Fifteen batches of the assembled SERS platform produced a relative standard deviation of 10.58% in the SERS intensity of the peak at 1178 cm^-1 generated in the presence of 0.08 ppm crystal violet, indicating that this strategy possesses good reproducibility. Furthermore, interfacial assembly allowed the dual-analyte detection of BBP in the organic phase and an edible pigment (sunset yellow) in the aqueous phase to be achieved with high sensitivity and credible reproducibility using the SERS platform. Interfacial self-assembled SERS-active arrays therefore show great potential for the rapid and sensitive in situ detection of BBP in liquor samples. Graphical abstract ᅟ.

Keywords: Au nanoparticle; Butyl benzyl phthalate; Interfacial self-assembled; Surface-enhanced Raman spectroscopy.